STATISTICAL METHODS FOR USE IN QUALITY CONTROL OF CONCRETE

Abstract

The quality of concrete placed in a structure determines the useful life of the work. Apart from the concrete ingredients viz water/cement ratio, quantity of cement, bulk and proportions of stones the qualityof control exercised in the preparation of concrete determines the ultimate strength and economy of batch. The philosophy underlying the concept of quality control in any construction is to produce. economically a structure, which is both structurally sound as well as functionally adequate. Cost of controlled concrete is always cheaper than that of un-controlled concrete, which requires much richer mix for the strength to remain within the tolerance level. Statistical methods provide tools of considerable value in assessing results of strength tests and such information is also of value in refixing design criteria and specifications. Statistics is a method of investigation that is used when other methods are of no avail. All the different methods of statistical controls for quality of concrete have been detailed. Various statistical terms and their use have been outlined so as to make field engineer to comprehend the utility and application of the different methods. This is the first ever attemp to collect at one place what various authorities do to control quality of concrete. Various statistical tools like use of standard deviation, coefficient of variation, normal distribution, F test, It$ test, control charts etc. have been explained with reference to concrete control and an example has been given to demonstrate the use.